1. Field of the Invention
The present invention relates to a metal ion eluting unit that elutes antibacterial metal ions into water, and an apparatus that uses water including the metal ions eluted by the metal ion eluting unit.
2. Description of the Related Art
Due to a growing female employment rate and the trend toward nuclear families in recent years, in more and more households, nobody stays home during the daytime. Such households frequently dry laundry indoors. Even households where someone stays home during the daytime dry laundry indoors in rainy times. In the indoor drying, bacteria and mold are more likely to propagate in the laundry than in the sun drying. This trend is more remarkable when it takes much time to dry laundry, such as in high humidity condition, e.g., rainy season, or low temperature condition. The laundry may give out foul smells, depending on the propagation condition. Therefore, households that ordinarily have no choice other than the indoor drying have a strong need for subjecting fabrics to an antibacterial treatment to suppress the propagation of bacteria and mold.
Recently, more and more clothes have textiles that are subjected to an antibacterial-deodorizing treatment or bacteria-control treatment. However, it is difficult to offer the household with textile products that are all subjected to an antibacterial-deodorizing treatment. Moreover, the effect of the antibacterial-deodorizing treatment decreases with the increasing number of washes.
Accordingly, technology has been proposed which subjects laundry to an antibacterial treatment in each wash. Patent document 1, for example, discloses an electric washing machine equipped with an ion generator that generates metal ions having sterilizing capability. Patent document 2 discloses a washing machine including a silver-ion-adding unit that adds silver ions to washing water.
Silver ions, copper ions, and the like are known as antibacterial metal ions. The silver ions in particular have been well known since early times to have sterilizing capability. Such antibacterial metal ions are characterized in that they are more stable than chlorine, maintains the sterilizing effect, and do not generate harmful substance.
The metal ion elution is generally performed by using an electrode type metal ion eluting unit. In the electrode type metal ion eluting unit, the application of a voltage between electrodes causes a current to flow between the electrodes, thereby eluting metal ions from the positive electrode in accordance with the Coulomb's law. The concentration of metal ions eluted is generally controlled by the volume of water flowing between the electrodes and the current flowing therebetween.
The electrode type metal ion eluting unit generally encounters a problem that calcium carbonate or the like deposits on the negative electrode, i.e., scale deposition. Thus, this scale deposition is generally prevented by periodically reversing the polarity of the voltage applied between the electrodes so that the positive and negative electrodes are periodically switched to each other.    Patent document 1 Japanese Utility Model Laid-open No. H5-74487    Patent document 2 Japanese Patent Application Laid-open No. 2001-276484